Water Purification in a Survival Scenario

Water Rain Pouring
Water Rain Pouring

When you find yourself in a survival scenario, it can be difficult to decide where to start. Your immediate thought might be “Oh my god, I’m going to die.” However, you must remember that panic is never helpful. You can easily get overwhelmed and give up, or potentially make your situation worse. You must slow down and break up survival into specific tasks.

Your four top priorities should be food, water, fire, and shelter. These are the four pillars of survival. 

Water is typically one of my first points of focus for survival. I know I will need it soon, so if there is a water source nearby then I always take advantage of that. Dehydration is the second most common way that people die during survival scenarios. You can only survive three days without water under normal circumstances. However, extreme exhaustion, high temperatures, or low temperatures can shorten that window. In addition, the initial phases of dehydration can make you physically weak and disoriented. It will drastically affect your ability to complete other tasks.

Some figures you can consider are that the average adult needs one gallon of water per day to stay hydrated under normal circumstances. In extreme heat or cold, you can count on two gallons per day. During a long-distance survival challenge last year, I dealt with heat during the day, cold at night, and 34 miles of hiking through rocky and steep terrain. I drank about three gallons of water per day and was still dehydrated at the end of the challenge. More importantly, if you do not purify the water that you drink you can count on becoming more dehydrated. Harmful pathogens in the water can cause diarrhea and vomiting along with other unpleasant symptoms. In this article, we will cover several different ways to purify your water in a survival scenario.

Finding Water

Of course, before you can purify water for drinking you must find water. This is not always easy, but you can find water sources in almost every environment if you know what to look for. For example, I am currently training for a long-distance challenge in Yellowjacket Canyon. This is located in the high desert so water is scarce. In addition, temperatures are high during the day and very low at night. However, I know that even in the driest canyons you can typically find pools of moisture in the rock at the base of the canyon.

This represents one of the most important principles for finding water. Low ground is a good place to start looking. This is where moisture is most likely to gather. You can also look for an area in which the vegetation is greener and healthier than other vegetation. These plants are likely getting more water than the others.

Game trails are another great indicator. Many animals follow the same paths to water on a daily basis, so following the game trails will likely take you to a water source. In especially cold climates, the snow and ice at the top of peaks can be a good source of moisture. However, ice is a much better source than snow. Ice is 90% water and 10% air while snow is 90% air and 10% water. Just be sure you melt it before consuming so you do not lower your body temperature.

Collecting Water that is Safe to Drink

There are a few sources of water that are relatively safe to drink as is. The one we most often think of is spring water. If you find water that is coming directly out of the ground, it is likely that the earth has already filtered the water for you. However, be sure you smell and taste the water before drinking. A foul smell or taste can indicate a buildup of harmful minerals that can make you sick. Another common option is runoff from snow or ice. This water is typically pure, but you must catch it high up on the mountain before it has had a chance to pick up impurities from lower on the mountain.

Rainwater is always a good option if you have a way to collect it. Sheets of plastic or certain types of plants can be used to catch rainwater and direct it into containers. In tropical climates, this may be your best bet. You may have seen people splitting open coconuts or prickly pear cactus for water. While this is an option, drinking too much can make you sick with diarrhea. Water collects in bamboo as well as water lines. If you cut off a section, you can get a drink of some safe water. Finally, if you are at sea and have no fresh water you can use fish. Saltwater fish have water in their spinal column that is safe to drink. Just insert your knife at the base of the spine until you feel a pop. Then drink from the hole.

Water Purification Devices

Straw Style Filter

There are several different types of filters you can purchase that can purify your water to 99.999% purity. These do a good enough job that you are almost guaranteed to be drinking safe water. One of the most popular is the straw style filter. This is a small filter designed to fit in your pocket. When you need a drink, you just lie down on the ground next to a water source and drink like it was a straw. However, some of these are unpleasant to use as the suction can cause sores in your mouth. In addition, you must get down on the ground to use it and you cannot take the purified water with you.

Filter Bottle

My favorite type of water filter is a filter bottle. This is a simple water bottle with a filter built into the lid. I can dip the bottle in a water source, screw on the lid, take it with me, and take a drink whenever I like. The mouthpiece is easier to use and requires little suction. As a side benefit, I can take this bottle with me anywhere I go and everybody just thinks it is a normal water bottle. They tend to clog if you are not careful, so be sure to blow all the water out of the filter and let it dry out before packing it away.

Pump and Gravity Systems

You can also get pump systems and gravity systems. A pump system is designed to use a hand pump to draw water from a source, through a filter, and into a container. However, you still need a separate container for the water. For a large group of people, a gravity system works well. It typically has a large bladder that holds several gallons of water. After hanging from a tree, gravity draws the water through a filter and then through a spout so everybody can fill their cups.

Chemical Purification

Another simple and compact way to purify water is through chemical purification. This uses certain chemicals to kill the bacteria and parasites you might find in your water. However, it does not remove debris so filtering is still a good idea. My preference is iodine tablets. For a few dollars, you can get a small vial with dozens of iodine tablets. To use these, I fill a container with water, drop one or two tablets into the water, and 30 minutes later it is good to drink. The more water you purify, the more tablets you use. The vial is small enough to fit in my pocket as well. For liquid solutions, you can use liquid bleach or liquid iodine, but then you have the potential for it spilling. The only real downside to chemical purification is having to wait 30 minutes to drink.

Water Purification Tablets


One of the oldest and most effective ways to purify water is by boiling it. The high temperatures required for boiling will kill bacteria and parasites. Like chemical purification, it does not remove debris so filtering is still suggested. When I was growing up, it was said that you need to boil water for 10 minutes before you could consume it. We now know that just bringing it to a roaring boil is good enough to make the water safe to drink. The downside is that you must build a fire and you must wait a few minutes for the water to boil and then for it to cool down enough to drink. You also must have a container that works for boiling. However, even a plastic bottle can be used for boiling if you suspend it from a tripod over the fire. The bottle will deform, but the water inside will keep it cool enough that it will not melt through.

Building a DIY Filter

If you do not have a filter and prefer this method of purification, you can build your own. First, start with a plastic bottle and cut the bottom off. Leave the cap on and just poke holes in it to keep the contents inside. Start by adding pieces of charcoal from your fire to the bottom. These should take up about 1/3 of the bottle. Next, add a layer of sand that takes up about 1/3 of the bottle. Then, add a layer of small stones that take up 1/3 of the bottle. Finally, tie a piece of cloth over the opening where the bottom was. As you dump water into your filter, the cloth removes some of the debris. The rock and sand should remove the rest. Then the charcoal removes chemicals and pathogens before it trickles out of the bottom into a container.

UV Purification

Another option to kill bacteria and parasites is using UV light. For this, you will need clear plastic bottles. Colored plastic and glass will not allow enough UV light into the bottle. You also much have direct sunlight and the water must be clear. Cloudy water will not work. Fill the bottles and set them out into the sun at the beginning of the day. They must sit in the sun for at least six hours, but all day is better. This should remove pathogens from the water, but will not remove debris. Filtering is still a good idea.

Proximity Well

As a last resort, you can dig a proximity well to purify water. This is designed to use the earth to filter out the water for you. Start digging a few feet from the edge of your water source. The well needs to be deep enough that the bottom is below the water level for your water source. The water should very slowly start to seep into the well and build up at the bottom. If the water is coming in quickly, your well is probably too close to the water source. Once the well is deep enough, give it at least 30 minutes for debris to settle to the bottom.

In Conclusion

As you can see, there are plenty of ways to purify your water in a survival scenario. The key is knowing what to do with the resources you have. It is also a good idea to have supplies with you for water purification before you ever head into the wild. I always keep a filter bottle, straw filter, iodine tablets, and a container for boiling in my pack so I have several different ways to purify water.

It is vital that you practice the use of these methods in advance before you ever end up in a survival scenario. In addition, test your equipment before each time that you might need to use it. There have been a few times I went into the wild planning on using my filters just to find out that they were clogged beyond repair. This was quite disheartening when it happened only an hour into my trip. With a little time and effort, you can ensure that you always have water that is safe to drink.

Leave a Comment: